China has banned foreigners from Tibet until after massive celebrations in Beijing marking the 60th birthday of communist China, a government tourism office and travel agents said on Tuesday.

China has banned foreigners from Tibet until after massive celebrations in Beijing marking the 60th birthday of communist China, a government tourism office and travel agents said on Tuesday.

A woman staffer at the official Lhasa Tourism Bureau in the regional capital said the ban would officially go into effect on Thursday.

"Passes for foreign travellers to enter Tibet will be suspended from September 24 to October 8. That's a notice from the Tibet Tourism Bureau," said the woman, who refused to give her name.

She said the notice contained no further information and no reason for the ban.

Officials with the regional government and Tibet Tourism Bureau refused to comment. Travel agents reached by AFP said the ban was already in place.

"It started from Monday, according to the notice from the Tibet Tourism Bureau. Passes for foreign travellers are suspended until October 8," said a woman staff member at the Tibet Youth Travel Service.

The move is the latest in a series of steps indicating intense official concerns over security ahead of National Day on October 1, when China will celebrate 60 years of communist rule.

The government already has sharply ramped up security in Beijing, putting thousands of extra police on the streets ahead of the festivities, which will include a military parade, fireworks and mass performances at Tiananmen Square.

State media reported Monday that outgoing flights would be halted at Beijing's airport during the parade, and retailers have said they have been banned from selling kitchen knives after two recent stabbings near the square.

Foreign tourists must obtain special permission from China's government to enter Tibet, the remote Himalayan region where resentment against Chinese control has seethed for decades.

China has previously banned foreign tourists from visiting Tibet, including after deadly anti-Chinese riots that erupted in Lhasa and across the Tibetan plateau in March 2008.

China also barred foreigners in March of this year during the tense 50th anniversary of a failed 1959 uprising against China that sent the Dalai Lama, the Tibetan spiritual leader, into exile.